William (Gulielmus) III (tertius) ruled Great Britain from 1694 to 1702. Your coin, Ronald, is no doubt dated 1697 rather than 1607, as the 9 is easily confused for a zero.

Back then a penny was worth so much they were minted in silver. But lesser denominations, farthings and half pennies, were also minted in copper. This page applies to copper coins only. These can be valuable, especially when in good condition. Coins with heavy wear, cleanings, or other damage are worth very little.